Vulnerable Colorado Republican Mike Coffman said Tuesday that he might skip the presidential race when he votes next month.

"I don't know if I'll vote for president," the 6th District congressman told Denver NBC affiliate 9News. "I'm not going to vote for Hillary Clinton or Donald Trump. I'm struggling with it like many Americans."

Coffman called on Trump to step aside as the GOP presidential nominee after the release of a 2005 "Access Hollywood" video in which Trump bragged about groping women.

Even before the recording came to light, the four-term congressman had made it clear that he wasn't a fan of Trump, even if he had never gone as far as saying he wouldn't vote for him.

In an August ad, Coffman said he didn't much like the nominee. A subsequent ad showed him turning off the television when both Trump and Clinton came on screen.

Coffman didn't rule out voting for Libertarian Party nominee Gary Johnson Tuesday but said the former New Mexico governor had said "dumb things" about foreign policy.

Coffman suggested Democrats could win the White House and Senate. House Republicans would need to provide a check on Democrat-controlled branches of government, he argued.

"How can we trust him to make decisions regarding national security, our economy or the direction of this country, if he refuses make the most important decision of all: voting on who will serve as commander in chief?" she said in a statement.

Democrats have been trying to tie Coffman to Trump, even after he called on him to step aside as the nominee. House Majority PAC, a Democratic super PAC, released an ad last week suggesting that Coffman set the stage for Trump.

"Before Donald Trump, there was Mike Coffman," the narrator says. The ad includes 2012 footage of Coffman saying that President Barack Obama is not an American.

In his Tuesday interview, Coffman called those 2012 remarks "boneheaded."